ui: add package input for merged input

To avoid passing a queue type for each kind of input (pointer, key),
introduce package input for mapping a handler key to all input events.

Future input sources can be added without changes to programs, and
as an added bonus, event ordering is preserved across input sources.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

ui/app/window.go

@@ -11,9 +11,9 @@ import (
 
 	"gioui.org/ui"
 	"gioui.org/ui/app/internal/gpu"
+	"gioui.org/ui/input"
 	"gioui.org/ui/internal/ops"
 	"gioui.org/ui/key"
-	"gioui.org/ui/pointer"
 )
 
 type WindowOptions struct {
@@ -238,9 +238,7 @@ func (w *Window) event(e Event) {
 	needAck := false
 	needRedraw := false
 	switch e := e.(type) {
-	case pointer.Event:
+	case input.Event:
-		needRedraw = true
-	case key.Event:
 		needRedraw = true
 	case *Command:
 		needAck = true

ui/gesture/gestures.go

@@ -9,6 +9,7 @@ import (
 
 	"gioui.org/ui"
 	"gioui.org/ui/f32"
+	"gioui.org/ui/input"
 	"gioui.org/ui/pointer"
 )
 
@@ -80,9 +81,13 @@ func (c *Click) Add(ops *ui.Ops) {
 	op.Add(ops)
 }
 
-func (c *Click) Update(q pointer.Events) []ClickEvent {
+func (c *Click) Update(q input.Events) []ClickEvent {
 	var events []ClickEvent
 	for _, e := range q.For(c) {
+		e, ok := e.(pointer.Event)
+		if !ok {
+			continue
+		}
 		switch e.Type {
 		case pointer.Release:
 			if c.State == StatePressed {
@@ -124,13 +129,17 @@ func (s *Scroll) Dragging() bool {
 	return s.dragging
 }
 
-func (s *Scroll) Update(cfg *ui.Config, q pointer.Events, axis Axis) int {
+func (s *Scroll) Update(cfg *ui.Config, q input.Events, axis Axis) int {
 	if s.axis != axis {
 		s.axis = axis
 		return 0
 	}
 	total := 0
 	for _, e := range q.For(s) {
+		e, ok := e.(pointer.Event)
+		if !ok {
+			continue
+		}
 		switch e.Type {
 		case pointer.Press:
 			if s.dragging || e.Source != pointer.Touch {

ui/input/input.go

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// Package input exposes a unified interface to input sources. Subpackages
+// such as pointer and key provide the interfaces for specific input types.
+package input
+
+// Events maps an event handler key to the events
+// available to the handler.
+type Events interface {
+	For(k Key) []Event
+}
+
+// Key is the stable identifier for an event handler. For a handler h, the
+// key is typically &h.
+type Key interface{}
+
+// Event is the marker interface for input events.
+type Event interface {
+	ImplementsInputEvent()
+}

ui/input/key.go

@@ -1,22 +1,22 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
-package key
+package input
 
 import (
 	"gioui.org/ui"
 	"gioui.org/ui/internal/ops"
+	"gioui.org/ui/key"
 )
 
-type Queue struct {
+type keyQueue struct {
 	focus    Key
-	handlers map[Key]*handler
+	handlers map[Key]*keyHandler
 	reader   ui.OpsReader
-	state    TextInputState
+	state    key.TextInputState
 }
 
-type handler struct {
+type keyHandler struct {
 	active bool
-	events []Event
 }
 
 type listenerPriority uint8
@@ -30,20 +30,19 @@ const (
 
 // InputState returns the last text input state as
 // determined in Frame.
-func (q *Queue) InputState() TextInputState {
+func (q *keyQueue) InputState() key.TextInputState {
 	return q.state
 }
 
-func (q *Queue) Frame(root *ui.Ops) {
+func (q *keyQueue) Frame(root *ui.Ops, events handlerEvents) {
 	if q.handlers == nil {
-		q.handlers = make(map[Key]*handler)
+		q.handlers = make(map[Key]*keyHandler)
 	}
 	for _, h := range q.handlers {
 		h.active = false
-		h.events = h.events[:0]
 	}
 	q.reader.Reset(root)
-	focus, pri, hide := q.resolveFocus()
+	focus, pri, hide := q.resolveFocus(events)
 	for k, h := range q.handlers {
 		if !h.active {
 			delete(q.handlers, k)
@@ -55,46 +54,33 @@ func (q *Queue) Frame(root *ui.Ops) {
 	changed := focus != nil && focus != q.focus
 	if focus != q.focus {
 		if q.focus != nil {
-			if h, ok := q.handlers[q.focus]; ok {
+			events[q.focus] = append(events[q.focus], key.Focus{Focus: false})
-				h.events = append(h.events, Focus{Focus: false})
-			}
 		}
 		q.focus = focus
 		if q.focus != nil {
-			// A new focus always exists in the handler map.
+			events[q.focus] = append(events[q.focus], key.Focus{Focus: true})
-			h := q.handlers[q.focus]
-			h.events = append(h.events, Focus{Focus: true})
 		}
 	}
 	switch {
 	case pri == priNewFocus:
-		q.state = TextInputOpen
+		q.state = key.TextInputOpen
 	case hide:
-		q.state = TextInputClosed
+		q.state = key.TextInputClosed
 	case changed:
-		q.state = TextInputFocus
+		q.state = key.TextInputFocus
 	default:
-		q.state = TextInputKeep
+		q.state = key.TextInputKeep
 	}
 }
 
-func (q *Queue) Push(e Event) {
+func (q *keyQueue) Push(e Event, events handlerEvents) {
 	if q.focus == nil {
 		return
 	}
-	h := q.handlers[q.focus]
+	events[q.focus] = append(events[q.focus], e)
-	h.events = append(h.events, e)
 }
 
-func (q *Queue) For(k Key) []Event {
+func (q *keyQueue) resolveFocus(events handlerEvents) (Key, listenerPriority, bool) {
-	h := q.handlers[k]
-	if h == nil {
-		return nil
-	}
-	return h.events
-}
-
-func (q *Queue) resolveFocus() (Key, listenerPriority, bool) {
 	var k Key
 	var pri listenerPriority
 	var hide bool
@@ -106,7 +92,7 @@ loop:
 		}
 		switch ops.OpType(encOp.Data[0]) {
 		case ops.TypeKeyHandler:
-			var op OpHandler
+			var op key.OpHandler
 			op.Decode(encOp.Data, encOp.Refs)
 			var newPri listenerPriority
 			switch {
@@ -122,17 +108,16 @@ loop:
 			}
 			h, ok := q.handlers[op.Key]
 			if !ok {
-				h = &handler{
+				h = new(keyHandler)
-					// Reset the handler on (each) first appearance.
-					events: []Event{Focus{Focus: false}},
-				}
 				q.handlers[op.Key] = h
+				// Reset the handler on (each) first appearance.
+				events[op.Key] = []Event{key.Focus{Focus: false}}
 			}
 			h.active = true
 		case ops.TypeHideInput:
 			hide = true
 		case ops.TypePush:
-			newK, newPri, h := q.resolveFocus()
+			newK, newPri, h := q.resolveFocus(events)
 			hide = hide || h
 			if newPri >= pri {
 				k, pri = newK, newPri

ui/input/pointer.go

@@ -1,16 +1,17 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
-package pointer
+package input
 
 import (
 	"gioui.org/ui"
 	"gioui.org/ui/f32"
 	"gioui.org/ui/internal/ops"
+	"gioui.org/ui/pointer"
 )
 
-type Queue struct {
+type pointerQueue struct {
 	hitTree  []hitNode
-	handlers map[Key]*handler
+	handlers map[Key]*pointerHandler
 	pointers []pointerInfo
 	reader   ui.OpsReader
 	scratch  []Key
@@ -25,22 +26,21 @@ type hitNode struct {
 }
 
 type pointerInfo struct {
-	id       ID
+	id       pointer.ID
 	pressed  bool
 	handlers []Key
 }
 
-type handler struct {
+type pointerHandler struct {
 	area      areaIntersection
 	active    bool
 	transform ui.Transform
-	events    []Event
 	wantsGrab bool
 }
 
 type area struct {
 	trans ui.Transform
-	area  OpArea
+	area  pointer.OpArea
 }
 
 type areaIntersection []area
@@ -51,7 +51,7 @@ type areaStack struct {
 	backing []area
 }
 
-func (q *Queue) collectHandlers(r *ui.OpsReader, t ui.Transform, layer int) {
+func (q *pointerQueue) collectHandlers(r *ui.OpsReader, t ui.Transform, layer int, events handlerEvents) {
 	for {
 		encOp, ok := r.Decode()
 		if !ok {
@@ -60,7 +60,7 @@ func (q *Queue) collectHandlers(r *ui.OpsReader, t ui.Transform, layer int) {
 		switch ops.OpType(encOp.Data[0]) {
 		case ops.TypePush:
 			q.areas.push()
-			q.collectHandlers(r, t, layer)
+			q.collectHandlers(r, t, layer, events)
 		case ops.TypePop:
 			q.areas.pop()
 			return
@@ -68,24 +68,22 @@ func (q *Queue) collectHandlers(r *ui.OpsReader, t ui.Transform, layer int) {
 			layer++
 			q.hitTree = append(q.hitTree, hitNode{level: layer})
 		case ops.TypeArea:
-			var op OpArea
+			var op pointer.OpArea
-			op.decode(encOp.Data)
+			op.Decode(encOp.Data)
 			q.areas.add(t, op)
 		case ops.TypeTransform:
 			var op ui.OpTransform
 			op.Decode(encOp.Data)
 			t = t.Mul(op.Transform)
 		case ops.TypePointerHandler:
-			var op OpHandler
+			var op pointer.OpHandler
 			op.Decode(encOp.Data, encOp.Refs)
 			q.hitTree = append(q.hitTree, hitNode{level: layer, key: op.Key})
 			h, ok := q.handlers[op.Key]
 			if !ok {
-				h = &handler{
+				h = new(pointerHandler)
-					// Reset the handler on (each) first appearance.
-					events: []Event{Event{Type: Cancel}},
-				}
 				q.handlers[op.Key] = h
+				events[op.Key] = []Event{pointer.Event{Type: pointer.Cancel}}
 			}
 			h.active = true
 			h.area = q.areas.intersection()
@@ -95,7 +93,7 @@ func (q *Queue) collectHandlers(r *ui.OpsReader, t ui.Transform, layer int) {
 	}
 }
 
-func (q *Queue) opHit(handlers *[]Key, pos f32.Point) {
+func (q *pointerQueue) opHit(handlers *[]Key, pos f32.Point) {
 	level := 1 << 30
 	opaque := false
 	for i := len(q.hitTree) - 1; i >= 0; i-- {
@@ -114,31 +112,30 @@ func (q *Queue) opHit(handlers *[]Key, pos f32.Point) {
 				continue
 			}
 			res := h.area.hit(pos)
-			opaque = opaque || res == hitOpaque
+			opaque = opaque || res == pointer.HitOpaque
-			if res != hitNone {
+			if res != pointer.HitNone {
 				*handlers = append(*handlers, n.key)
 			}
 		}
 	}
 }
 
-func (q *Queue) init() {
+func (q *pointerQueue) init() {
 	if q.handlers == nil {
-		q.handlers = make(map[Key]*handler)
+		q.handlers = make(map[Key]*pointerHandler)
 	}
 }
 
-func (q *Queue) Frame(root *ui.Ops) {
+func (q *pointerQueue) Frame(root *ui.Ops, events handlerEvents) {
 	q.init()
 	for _, h := range q.handlers {
 		// Reset handler.
 		h.active = false
-		h.events = h.events[:0]
 	}
 	q.hitTree = q.hitTree[:0]
 	q.areas.reset()
 	q.reader.Reset(root)
-	q.collectHandlers(&q.reader, ui.Transform{}, 0)
+	q.collectHandlers(&q.reader, ui.Transform{}, 0, events)
 	for k, h := range q.handlers {
 		if !h.active {
 			q.dropHandler(k)
@@ -146,18 +143,7 @@ func (q *Queue) Frame(root *ui.Ops) {
 	}
 }
 
-func (q *Queue) For(k Key) []Event {
+func (q *pointerQueue) dropHandler(k Key) {
-	if k == nil {
-		panic("nil handler")
-	}
-	h := q.handlers[k]
-	if h == nil {
-		return nil
-	}
-	return h.events
-}
-
-func (q *Queue) dropHandler(k Key) {
 	delete(q.handlers, k)
 	for i := range q.pointers {
 		p := &q.pointers[i]
@@ -169,9 +155,9 @@ func (q *Queue) dropHandler(k Key) {
 	}
 }
 
-func (q *Queue) Push(e Event) {
+func (q *pointerQueue) Push(e pointer.Event, events handlerEvents) {
 	q.init()
-	if e.Type == Cancel {
+	if e.Type == pointer.Cancel {
 		q.pointers = q.pointers[:0]
 		for k := range q.handlers {
 			q.dropHandler(k)
@@ -190,7 +176,7 @@ func (q *Queue) Push(e Event) {
 		pidx = len(q.pointers) - 1
 	}
 	p := &q.pointers[pidx]
-	if !p.pressed && (e.Type == Move || e.Type == Press) {
+	if !p.pressed && (e.Type == pointer.Move || e.Type == pointer.Press) {
 		p.handlers, q.scratch = q.scratch[:0], p.handlers
 		q.opHit(&p.handlers, e.Position)
 		// Drop handlers no longer hit.
@@ -203,7 +189,7 @@ func (q *Queue) Push(e Event) {
 			}
 			q.dropHandler(h)
 		}
-		if e.Type == Press {
+		if e.Type == pointer.Press {
 			p.pressed = true
 		}
 	}
@@ -223,7 +209,7 @@ func (q *Queue) Push(e Event) {
 			q.dropHandler(k)
 		}
 	}
-	if e.Type == Release {
+	if e.Type == pointer.Release {
 		q.pointers = append(q.pointers[:pidx], q.pointers[pidx+1:]...)
 	}
 	for i, k := range p.handlers {
@@ -231,14 +217,14 @@ func (q *Queue) Push(e Event) {
 		e := e
 		switch {
 		case p.pressed && len(p.handlers) == 1:
-			e.Priority = Grabbed
+			e.Priority = pointer.Grabbed
 		case i == 0:
-			e.Priority = Foremost
+			e.Priority = pointer.Foremost
 		}
-		e.Hit = h.area.hit(e.Position) != hitNone
+		e.Hit = h.area.hit(e.Position) != pointer.HitNone
 		e.Position = h.transform.InvTransform(e.Position)
-		h.events = append(h.events, e)
+		events[k] = append(events[k], e)
-		if e.Type == Release {
+		if e.Type == pointer.Release {
 			// Release grab when the number of grabs reaches zero.
 			grabs := 0
 			for _, p := range q.pointers {
@@ -253,19 +239,19 @@ func (q *Queue) Push(e Event) {
 	}
 }
 
-func (a areaIntersection) hit(p f32.Point) hitResult {
+func (a areaIntersection) hit(p f32.Point) pointer.HitResult {
-	res := hitNone
+	res := pointer.HitNone
 	for _, area := range a {
 		tp := area.trans.InvTransform(p)
-		res = area.area.hit(tp)
+		res = area.area.Hit(tp)
-		if res == hitNone {
+		if res == pointer.HitNone {
 			break
 		}
 	}
 	return res
 }
 
-func (s *areaStack) add(t ui.Transform, a OpArea) {
+func (s *areaStack) add(t ui.Transform, a pointer.OpArea) {
 	s.areas = append(s.areas, area{t, a})
 }
 

ui/input/queue.go

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package input
+
+import (
+	"gioui.org/ui"
+	"gioui.org/ui/key"
+	"gioui.org/ui/pointer"
+)
+
+// Queue is an Events implementation that merges events from
+// all available input sources.
+type Queue struct {
+	pqueue pointerQueue
+	kqueue keyQueue
+
+	handlers handlerEvents
+}
+
+type handlerEvents map[Key][]Event
+
+func (q *Queue) For(k Key) []Event {
+	return q.handlers[k]
+}
+
+func (q *Queue) Frame(ops *ui.Ops) {
+	q.init()
+	for k := range q.handlers {
+		delete(q.handlers, k)
+	}
+	q.pqueue.Frame(ops, q.handlers)
+	q.kqueue.Frame(ops, q.handlers)
+}
+
+func (q *Queue) Add(e Event) {
+	q.init()
+	switch e := e.(type) {
+	case pointer.Event:
+		q.pqueue.Push(e, q.handlers)
+	case key.Edit, key.Chord, key.Focus:
+		q.kqueue.Push(e, q.handlers)
+	}
+}
+
+func (q *Queue) InputState() key.TextInputState {
+	return q.kqueue.InputState()
+}
+
+func (q *Queue) init() {
+	if q.handlers == nil {
+		q.handlers = make(handlerEvents)
+	}
+}

ui/key/key.go

@@ -16,14 +16,6 @@ type OpHideInput struct{}
 
 type Key interface{}
 
-type Events interface {
-	For(k Key) []Event
-}
-
-type Event interface {
-	isKeyEvent()
-}
-
 type Focus struct {
 	Focus bool
 }
@@ -93,9 +85,9 @@ func (h OpHideInput) Add(o *ui.Ops) {
 	o.Write(data)
 }
 
-func (Edit) ImplementsEvent()  {}
+func (Edit) ImplementsEvent()       {}
-func (Chord) ImplementsEvent() {}
+func (Chord) ImplementsEvent()      {}
-func (Focus) ImplementsEvent() {}
+func (Focus) ImplementsEvent()      {}
-func (Edit) isKeyEvent()       {}
+func (Edit) ImplementsInputEvent()  {}
-func (Chord) isKeyEvent()      {}
+func (Chord) ImplementsInputEvent() {}
-func (Focus) isKeyEvent()      {}
+func (Focus) ImplementsInputEvent() {}

ui/layout/list.go

@@ -8,6 +8,7 @@ import (
 	"gioui.org/ui"
 	"gioui.org/ui/draw"
 	"gioui.org/ui/gesture"
+	"gioui.org/ui/input"
 	"gioui.org/ui/pointer"
 )
 
@@ -64,7 +65,7 @@ func (l *List) Dragging() bool {
 	return l.scroll.Dragging()
 }
 
-func (l *List) Update(c *ui.Config, q pointer.Events) {
+func (l *List) Update(c *ui.Config, q input.Events) {
 	l.Distance = 0
 	d := l.scroll.Update(c, q, gesture.Axis(l.Axis))
 	l.scrollDir = d

ui/pointer/pointer.go

@@ -37,16 +37,12 @@ type OpHandler struct {
 
 type Key interface{}
 
-type Events interface {
+type HitResult uint8
-	For(k Key) []Event
-}
-
-type hitResult uint8
 
 const (
-	hitNone hitResult = iota
+	HitNone HitResult = iota
-	hitTransparent
+	HitTransparent
-	hitOpaque
+	HitOpaque
 )
 
 type ID uint16
@@ -103,7 +99,7 @@ func (op OpArea) Add(o *ui.Ops) {
 	o.Write(data)
 }
 
-func (op *OpArea) decode(d []byte) {
+func (op *OpArea) Decode(d []byte) {
 	if ops.OpType(d[0]) != ops.TypeArea {
 		panic("invalid op")
 	}
@@ -118,10 +114,10 @@ func (op *OpArea) decode(d []byte) {
 	}
 }
 
-func (op *OpArea) hit(pos f32.Point) hitResult {
+func (op *OpArea) Hit(pos f32.Point) HitResult {
-	res := hitOpaque
+	res := HitOpaque
 	if op.Transparent {
-		res = hitTransparent
+		res = HitTransparent
 	}
 	switch op.kind {
 	case areaRect:
@@ -129,7 +125,7 @@ func (op *OpArea) hit(pos f32.Point) hitResult {
 			0 <= pos.Y && pos.Y < float32(op.size.Y) {
 			return res
 		} else {
-			return hitNone
+			return HitNone
 		}
 	case areaEllipse:
 		rx := float32(op.size.X) / 2
@@ -141,7 +137,7 @@ func (op *OpArea) hit(pos f32.Point) hitResult {
 		if xh*xh*ry2+yk*yk*rx2 <= rx2*ry2 {
 			return res
 		} else {
-			return hitNone
+			return HitNone
 		}
 	default:
 		panic("invalid area kind")
@@ -206,4 +202,5 @@ func (s Source) String() string {
 	}
 }
 
-func (Event) ImplementsEvent() {}
+func (Event) ImplementsEvent()      {}
+func (Event) ImplementsInputEvent() {}

ui/text/editor.go

@@ -11,6 +11,7 @@ import (
 	"gioui.org/ui"
 	"gioui.org/ui/draw"
 	"gioui.org/ui/gesture"
+	"gioui.org/ui/input"
 	"gioui.org/ui/key"
 	"gioui.org/ui/layout"
 	"gioui.org/ui/pointer"
@@ -53,7 +54,7 @@ const (
 	maxBlinkDuration = 10 * time.Second
 )
 
-func (e *Editor) Update(c *ui.Config, pq pointer.Events, kq key.Events) {
+func (e *Editor) Update(c *ui.Config, q input.Events) {
 	if e.cfg == nil || c.PxPerDp != e.cfg.PxPerDp || c.PxPerSp != e.cfg.PxPerSp {
 		e.invalidate()
 	}
@@ -68,7 +69,7 @@ func (e *Editor) Update(c *ui.Config, pq pointer.Events, kq key.Events) {
 		axis = gesture.Vertical
 		smin, smax = sbounds.Min.Y, sbounds.Max.Y
 	}
-	sdist := e.scroller.Update(c, pq, axis)
+	sdist := e.scroller.Update(c, q, axis)
 	var soff int
 	if e.SingleLine {
 		e.scrollOff.X += sdist
@@ -78,7 +79,7 @@ func (e *Editor) Update(c *ui.Config, pq pointer.Events, kq key.Events) {
 		soff = e.scrollOff.Y
 	}
 	scrollTo := false
-	for _, evt := range e.clicker.Update(pq) {
+	for _, evt := range e.clicker.Update(q) {
 		switch {
 		case evt.Type == gesture.TypePress && evt.Source == pointer.Mouse,
 			evt.Type == gesture.TypeClick && evt.Source == pointer.Touch:
@@ -92,7 +93,7 @@ func (e *Editor) Update(c *ui.Config, pq pointer.Events, kq key.Events) {
 		}
 	}
 	stop := (sdist > 0 && soff >= smax) || (sdist < 0 && soff <= smin)
-	for _, ke := range kq.For(e) {
+	for _, ke := range q.For(e) {
 		e.blinkStart = c.Now
 		switch ke := ke.(type) {
 		case key.Focus: